PhD Defence Michèlle van der Does

Publication date: Friday 07 December 2018

Category: DUST

As of today, Michèlle van der Does may call herself a PhD; she successfully defended her thesis "Saharan dust from a marine perspective: transport and deposition along a transect in the Atlantic Ocean" at the Vrije Universiteit Amsterdam. A committee of six experts in the field of mineral-dust transport, meteorology and marine environmental sciences discussed the main results that Michèlle described in her PhD thesis and unanimously judged her worthy of the title.

Here you see how PhD student Michèlle defends her thesis flanked by her two helpers (in Dutch: paranimfs) Laura and Laura.

The day before the thesis defence, a mini-symposium was organised at VU in which Michèlle already presented her work and discussed with the committee members. Most of the opponents also presented their work related to the source-to-sink changes of mineral dust, how to study this and why it matters.

A view from the audience (courtesy Frank Peeters, VU). On the left you see Michèlle answering the questions of the committee members sitting behind the table.

Seldom do you see a PhD committee that is so relaxed as this one; we were confident that Michèlle would do a great job!

Why are we so interested in dust?

It turns out that there are many direct and indirect links between dust and climate. The most straightforward one is fine-grained dust in the upper atmosphere blocking incoming sunlight, causing a net cooling effect. But there are warming effects too; in the lower atmosphere, coarser-grained dust particles absorb energy that was refelected at the earth's surface and this way, dust acts as a greenhouse gas.

There are many more negative and positive climate-related effects but the main link to the ocean is the fact that marine life may profit from nutrients in dust. When plankton reproduces, it takes up CO2 from the atmosphere. Thus, dust could potentially act as an ocean fertilizer, sequestering a greenhouse gas!